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Chicken pox incidence dropping, study shows

A study by the Centers for Disease Control and Prevention has shown that the number of Americans sent to the hospital each year for the chicken pox has dropped by 71 percent since routine vaccination began in 1995.

The new study showed that after vaccination against the varicella virus that causes chicken pox began, the yearly rates of infection fell 80 to 90 percent over the following decade, Reuters reports.

The symptoms for chicken pox include fever, an itchy blister-like rash, headache and fatigue, though some people also develop possibly serious complications. The complications can include vomiting, dehydration, inflammation of the brain and pneumonia.

Hospitalizations for chicken pox complications were steady at 0.1 for every 10,000 people between 2000 and 2006 in the United States, compared with a rate of 0.4 per 10,000 people between 1988 and 1995, according to Reuters. Researchers estimate that the vaccination prevented close to 50,000 hospitalizations between 2000 and 2006.

“This further supports what we’ve been seeing – in that there have been great declines in severe (chicken pox) disease,” Adriana S. Lopez, lead researcher, said, according to Reuters.

Lopez said that while hospitalizations have dropped, children aged four and younger have the highest rate of severe illness at 0.7 hospitalizations per 10,000 children between 2000 and 2006.

“It’s still important for parents to have their children vaccinated,” Lopez said, Reuters report.

The vaccine includes a first dose given between the ages of 12 months and 18 months. In 2007 a second dose was added to be given to those between the ages of four and six years of age. The vaccine was recommended for teenagers and adults to give a sort of “herd immunity” and reduce disease transmission.

The vaccine was found to have side effects, with about 20 percent of people reporting soreness or swelling at the injection site. Up to four percent have a mild rash and a few skin bumps that may resemble chicken pox. Serious side effects are rare and less than one in 1,000 recipients had fever-induced seizures. Problems like pneumonia and encephalitis are reported for two out of every 100,000 who receive the vaccine.